Chusetts



March 11 1924. 1,486,229

. H. H. CLARK IITERRUPTER MECHANI SM Filed June 25 1920 ATTORNEYS.

Patented Mar. 11, 1924.

UNITED STATES 1,486,229 PATENT OFFICE.

HAROLD H. CLARK, OF SPRINGFIELD, MASSACHUSETTS, ASSIGNQR '10 WICOELECTRIC COMPANY, OF SPRINGFIELD, MASSACHUSETTS, .A CORPORATION OFMASSA- CHUSETTS.

INTERRUPTER MECHANISM.

Application flledlune 25, 1920. Serial No. 391,608.

Springfield, in the county of Hampden and State of Massachusetts, haveinvented new and useful Improvements in Interrupter Mechanism, of whichthe following is a specification.

This invention relates to improvements in interrupter mechanism which,although capable of other applications, is particularly adapted for usewith ma etos. The invention is especially suitable for the diflicultwork of sharpl closin holding closed, and subsequently s arply reakingof an electrical circuit all within an exceedingly short interval.

An example of a magneto of a character which particularly necessitatesthe use oi interrupter mechanism of the character alluded to, is thefiywheel type of magneto. In the flywheel magneto, the relative movementbetween the armature and the cores is obtained by mounting one,preferably the armature, on the flywheel. The armature periodi ally, asfor example once on each revolution of the flywheel, moves into closeproximity to the cores to establish a magnetic circuit therethrough andvery shortly afterwards leaves the cores to interrupt the magneticcircuit thus established. The angular movement of the armature from theposition in which it makes to that in which it breaks the magneticcircuit is very small and'may, for example, be no more than onefiftiethpart of one revolutionofthe flywheel. Thus, with an internal combustionengine operating at 1200 revolutions per .minute, the time of the smallangular movement mentioned may be no more than one thousandth part of asecond.

During this same very small interval, it is desired to quickly close thebreaker points (which short circuit the primary windin of the cores ofthe magneto), hold them closed for an interval, and then sharply openthem. The usual interrupter mechanism embodying fixed and movablebreaker points with the latter actuated by a single cam, is not suitablefor accomplishing the results desired, because given a cam that willproduce a practically instantaneous closing, such cam cannot obviouslyproduce a practically instantaneous opening. That is, an abrupt radialdrop of the cam follower on the 'cam cannot be shortly afterwardsaccompanied by an abrupt radial rise. One or the other movement of thecam follower must needs be accomplished less rapidly and less sharplythan the other. This invention is concerned with interrupter mechanismwhich is ada ted among other things, to the solution of the aboveproblem.

An object of the invention is to provide improved interrupter mechanism,involvin breaker points, which may be sharply close and, after a .veryshort interval, sharply separated.

Another object of the invention is to provide, in interrupter mechanism,cooperatin and relatively movable breaker. points wit actuatingmechanism therefor, which is designed to permit the breaker points to besharply brought into engagement at all times irrespective of wear on thepoints.

Another object of the invention is to provide, in interrupter mechanismof the ty wherein cooperating breaker ints are he (1 in contact underspring. tension, means for releasing such tension at about the time ofopening the breaker points, whereby the resistance to movement of themovable breaker point is greatly reduced to permit quick accelerationthereof.

Another object of the invention is to provide means for se varating thebreaker points with a hammer low action to produce an exceedingly rapidseparation thereof.

Another obgect of the invention is to utilize the tension of the spring,when released at'or about the time of separation of the breaker points,as a means for actuating the hammer blow separating means.

Another object of the invention is to provide means for retensioning thespring, after its release without closing the breaker points.

Other objects and advantages will appear in the following descriptionand in the illustrative embodiment of the invention in the 190accompanying drawings, in which:

Fig. 1 is an elevational view showing an engine provided with a magnetoof a type with'which the interrupter mechanism may advantageously beused;

Fig. 2 is an enlarged front elevational view of the interruptermechanism, the cover of its enclosing casing being removed;

Fig. 3 is an enlarged side elvational view of the actuating cams;

Fig. i is an enlarged bottom plan view of the cam followers;

Fig. 5 is a cross sectional view taken on the line 5-5 of Fig. 3 anddrawn to a somewhat smaller scale;

Fig. 6 is a diagrammatical view of the essential parts of the magnetoshowing their relation with the interrupter mechanism; and

Fig. 7 is a fragmentary elevational view of a. modification in themounting of the breaker points.

Referring to these drawings: A represents a well-known type of internalcombustion engine, which, since'the invention is independent of, and notconcerned with, the structural details thereof, has been illustrated inconventional form only. For the present purposes, it will sufilce tostate that c is its flywheel and d the cam shaft. T he latter drives theinterrupter mechanism which is housed in a casing 6 having a cover g.

The magneto chosen to illustrate this invention, embodies a source ofmagnetic flux, as a permanent magnet k; a suitable primary generatingwinding, as the coils i; a secondary generating winding, as the coils j;cores is connected to opposite poles of the source it and extendingthrough the coils i; and an armature Z to periodically bridge the freeends of cores 7:. All these elements, except the armature Z, arestationarily mounted in proximity to the flywheel c as indicated in Fig.l. The armature Z, however, is attached to the tiywheel c and arrangedto move once each revolution into close proximity to the ends of coresFa to establish a magnetic circuit therethrough. The full lines in Fig.6 show the armature in such position and the dotted lines showtheposition of the armature at or about the time that the magneticcircuit, thus established, is broken. It will be apparent that the timetaken by the armature in moving from the full line to the dotted lineposition is exceedingly small;usuaily merely an exceedingly smallfraction a second.

The secondary coils j are electrically connected in series and one iselectrically connected to the spark plug on as conventionally indicatedin l primary coils 2' are likewise connected in series and one of theirtermin as it, is grounded. The other terminal connected by wire to oneof the breaker oint, as 3.0, later to be described and the other bread"-er point, as 11, is grounded. condenser 39 is bridged across the breakerpoints in the usual manner.

The breaker points it) and 11 are normally maintained in separatedrelatio leaving the primary winding open circuit- 7. This is desirablein order to permit the flux to idly build up in cores It, which actionwould be impeded if the primary winding were short circuited. Having theflux established to a maximum in cores it, it is then. feasible to closethe breaker points 10, and 11, and this is done, as near as may be, atthe time above defined. The armature Z, at such time, is approximatelyin the full line position shown in Fig. 6. The points 10 and 11 are thenheld closed until at or about the time of breaking of the magneticcircuit. At such time the armature Z is approximately in the dotted lineposition. In defining the times for closing and opening, I have done soby giving as nearly as possible the relative positions of the armatureand cores. These positions may, of course, be varied within limits but Ihave given those which I deem preferable.

In addition to the elements of the magneto, as described, there ispreferably pro vided a second path for the flux from the magnetic sourceh. This path is one of constant and relatively high reluctance and maybe made up of a series of laminations g, which are stacked face to facebetween the cores 70, as diagrammatically indicated in Fig. 6. Theselaminations q afford a path of greater reluctance than that through thecores Z; and armature Z when the latter is in position to magneticallyconnect the core ends. Such path, however, is of considerably lessreluctance than that through the cores when the armature is otherwisepositioned. Consequently, a large part of the flux then flows throughthe laminations g, which. then function something like a keeper for themagnets h and prevent undue loss of magnetism.

lhe presentinvention, being concerned more particularly with theinterrupter mechanism, is largely independent of the details of themagneto and the mechanism may well be used under many other conditionsthan those described. Particular pains, however, have'been taken todisclose in some detail the magneto structure realizing that it presentsan illustrative example of most severe conditions to be met by theinterrupter mechanism,

Referring now to Figs. 2 to inclusive, the fixed breaker point ismounted, preferably arljustably as indicated, in a bracket 12, which issuitably secured to and insulated from the back of the shell likeinterrupter casing e. The movable breaker point 11 is carried on the endof an arm 13, which is pivotally mounted on a stud 1a projecting fromthe back of casing e, and the. latter, be- 1':- frame, constitutes theground conventionally indicated in Fig. 6. The arm 13 may advantageouslybe struck up from sheet metal and provided with depending side webs 15,through and between which a bushlti extends, the latter being free toturn metallic and connected to the engine on stud Beneath the arm 13,which is relatively wide, are two cams 1'7 and which are mounted on thedescribed shaf d as will appear,.and a part of arm 13', overlying thecam 17, is bent downwarly to form a follower 19 for such cann A secondarm 20, formed similarly to arm 13 with side webs 21, is pivotallymounted on the bushing 16 and is free to turn independently of arm 13..The free end of arm. 20 bears a follower 22 for engagement with cam 18,the offset relation. of followers 1. an beingclearly shown in Fig 1. Thearms 13 and 20, which are normally substantially at right angles, areconnected, as by a coil spring 23, so as to be yieldin ly drawn towardone another, and. so as to hold the followers 19 and. 22 on theirrespective cams. Fixed to arm 20, as by being formed inte grally withone web 21, is a hammer arm at which underlies and is normally spacedfrom the arm 13.

The cams 1'7 and 18 are suitably fixed together, as for example, by thescrews 25.

('Fig. 2) which may, as shown, pass through slots 26 in cam 17, wherebythe relative angu lar positions of the cams may be adjusted if desired.The came 17 and 18 are preferably loosely mounted on. a hub 27 (Fig. 3)which is suitably fixed to the shaft 0?. Such hub has a flange 28against which the end face of cam 18 abuts, and a split ring '29sprung'into a groove in hub 27 cooperates with flange 28 to hold thecams against axial displacement. Cam 18, in its end face, is recessed toafford a shoulder 30 and an inclined surface 31leading from the base ofthis shoulder to the said end face, thereby affording the equivalent ofa single ratchet tooth. Slidable in flange 28 is a pawl 32, the innerencLof which is normally engaged with shoulder 30 to drive the latter inthe direction of the arrow shown in Fig. 3. On movement of shaft of inthe reverse direction, as on backfiring, the pawl 32 is raised out ofengagement with shoulder 30 by the-surface 31 and the cams are thereforenot then driven. A spring 33 tends to hold pawl 32 in its inner andshoulder-engaging position.

Each of the earns 17 and 18 are formed as true cylindrical surfacesconcentric with shaft of. Each, however, has a cut in its periphery toafford a radial surface or let off portion and a relatively gradual risefrom such portion to the circular surface of the cam. The radialsurfaces of cams 17 and '18 are indicated at 34 and 35 respectively andthe gradual rise at 36 and 37 respectively.

The shoulders 34 and 35 are sospaced that, when the cams rotate in thelanned direction, the follower 19 will be all by shoulder 35 before thefollower 22 reaches the shoulder 34. This condition is shown in Fig. 2and the drop of follower 19, while fol-- lower 22 is still held to thecircular portion owed to drop of its cam 17 allows the breaker points 10and 11 to he sharply and aunost instantaneously closed by thecontraction. of spring 23. The breaker points are irtaiued closed for ashort interval while follower 22 is moving from the illustrated positionto the shoulder 34, it being noted that, during this slight movement ofthe cams, the surface 37 will not have lifted the follower 19, As soonas shoulder'34 permits follower 22 to drop, the spring 23 contracts andits tension. is expended in quickly moving the arm 20 and its connectedhammer arm 24. The parts 20 and 24;, being light and at such timeencountering practically no resistance to movement, accelerate rapidlyand, by the time sistance (since the tension. of spring 23 has beenentirely released) and thus is rapidly and almost instantaneously moved.The follower 19 is released by shoulder 35 at or about the time thatarmature Z comes into the position shown in full lines in Fig. (i, andthe follower 22 is released by shoulder 34: at or about the time thatarmature Z reaches the osition shown in. dotted lines in. Fig. 6. T epoints 10 and 11, having been thus separated do not again immediatelyclose. During the outward flight of arm 13, under the force of hammer24, the cams l7 and 18 continue to turn and, by the time that gravityreturns arm 13, the cam 18 has moved sufficiently so that the follower19 drops onto the surface 37 at a point such as to prevent re-engagementwith the breaker points. In connection with the outward flight of arm13, it is to be noted that the arm is not suddenly arrested by abutmentwith fixed parts in a manner such as to produce noise and cause rapidwear. The arm, in its outward movement, is arrested by the spring 23 andthus yieldingly without sharp impact. on continued movement of the cams,the followers 19 and 22 are raised, the former slightly in advance ofthe latter and thev raising of the followers separate arms 13 and 20causing spring 23 to be re tensioned with out closing the breaker points10 and 11.

It has been found that the movable breaker point will, under someconditions, rebound after its engagement with the fixed breaker pointand produce a separation of the points at an undesired time. Thepremature separation of the breaker points can be prevented by reducingthe gap between them when in separated relation. Another way ofpreventing this undesired action, and one which is advantageous since itpermits a relatively large gap between the points, is illustrated inFig. 7. As there shown, the relatively fixed point 10 is mounted on theend of a thin arm 40, preferably of spring metal, which arm is securedat its other end to a bracket 12' mounted in the interrupter casing esimilarly to the bracket 12, heretofore described. Between the free endof arm and the adjacent portion of bracket 12 is placed a pad 41 ofsuitable material, such as felt for example. The point 11 when movedagainst point 10 moves arm 40 against pad 41 whieh yields to absorb theshock due to the engagement of the points. The pad 40 functions as acushioning or damping means and prevents the rebounding of the point 11and thus a premature separation of the points. The pad 41 also lessensthe shock of engagement of the points, but also lessens the wear on thelatter.

It will thus be seen that the invention provides an interruptermechanism, which while capable of use under the conditions ordinarilyencountered, is characterized in that it is also capable of meeting thespecial conditions and exacting requirements of flywheel magnetos of thegeneral character disclosed. It permits rapid and, for all practicalpurposes, instantaneous closing of the breaker points followed, after anexceedingly short interval, by an equally sharp and rapid opening of thebreaker points. Not only are the breaker points sharply closed but theyare closed and opened at given angular positions of the armatureindependently of wear. such as wear of the points themselves or of thecam follower or cam and this is of vital importance where, as here, solittle variation is tolerable in the angular position of the armatureboth at the instant of opening and at the instant of closing the points.

In connection with wear of parts, it should be noted that the mechanismis so designed as to reduce wear, by eliminating as far as possibleblows under the pressure which are productive of wear. Of especialimportance, due to the very small time intervals available for action,is the elimination, so far as possible, of resistance to motion of thecam followers and connected parts. Such parts are, to begin with, madelight and therefore have little inertia. The arm 20 and hammer arm 24,at the start of their movement when released by shoulder 34, meet withno appreciable resistance and thus accelerate quickly and rapidlyacquire velocity for the delivery of the hammer blow upon the arm 13. Atthe time of such blow the tension of spring 23 is relaxed so that arm13encounters no appreciable resistance and accordingly is moved almostinstantaneously to separate the breaker points.

The invention has been disclosed herein, in an embodiment at presentpreferred, for illustrative purposes, but the scope of the invention isdefined by the appended claims rather than by the foregoing description.

What I claim is 1. Interrupter mechanism, comprising, co-

operating and relatively movable breaker points, rotary timing mechanismfor controlling the opening and closing of said points, means operablefrom said mechanism at predetermined times to move said points intoengagement at a speed independent of its rotative speed, and meanssubsequently operable from said mechanism to move said points intoseparated relation and at a speed independent of its rotative speed.

2. interrupter mechanism, comprising, fixed and movable breaker points,a cam for holding the latter away from the former and for periodicallysuddenly releasing the latter for free movement into engagement with theformer, a hammer member adapted to suddenly separate the breaker points,and a second cam for normally holding said member in inactive positionand for periodically suddenly releasing said member to cause theseparation of the breaker points.

3. Interrupter mechanism, comprising, a fixed breaker point, a movablemember carrying a cooperating breaker point, a cam for holding saidmember so positioned that the breaker points are separated and forperiodically suddenly releasing it to permit engagement of said points,a hammer member for engagement with the first named member to causeseparation of said points, a second cam for holding the hammer memberdisengaged from the other member and periodically suddenly releasing it,and means for moving both said members.

4. Interrupter mechanism, comprising, a fixed breaker point, a movablemember carryin a cooperating breaker oint, a cam for holding said memberso positioned that the breaker points are separated and for periodicallysuddenly releasing it to permit engagement of said points, a hammermember for engagement with the first named member to cause separation ofsaid points, a second cam for holding the hammer member disengaged fromthe other member and, periodically suddenly releasing it, and yieldablemeans tending to hold said members in engagement with their cams and foractuating either member when released by its cam.

5. Interrupter mechanism, comprising, c0- operating and relativelymovable breaker points, rotary timing mechanism for controlling theopening and closing of said points, means operable from said mechanismat predetermined times to move said oints into engagement at a speedinde en ent of its rotative speed, and means su sequently operable fromsaid mechanism at a definite time after the operation of the first namedmeans to move said points into separated relation and at a speedindependent of its r0- tative speed.

6. Interrupter mechanism, comprising, a fixed breaker point, a movablemember carrying a cooperating breaker point, a cam IOU having a dwellportion for normally holding said member in such position that saidpoints are separated and a let off portion for suddenly releasing saidmember and permitting said points to be engaged, a movable hammer memberadapted to engage and move the first member, a cam having a dwellportion for normally holding the hammer member out of engagement withthe other member and resilient means urging said members toward theirrespective cams, said second cam having a let off portion to suddenlyrelease the hammer member at a predetermined time interval after therelease of the first member and move the latter to disen age saidpoints.

nterrupter mechanism, com rising, cooperating relatively fixed anmovable breaker points, a cam follower connected with the movablebreaker point, a cam for said follower connected with the movable fixedbreaker point, a pivoted arm carrying.

a cooperating bre'aker point, an actuating cam for said arm, said camhaving a dwell portion for holding the .arm so positioned that thepoints are separated, a'let ofi portion for suddenly releasing the armfor free movement, and a gradual rise from the latter to the formerportion; a second pivoted arm having a part adapted when the arm isreleased to engage and suddenly move the first arm, an actuating cam forthe second arm, said cam having a dwell portion to hold the second awayfrom the first arm,

a let off portion to suddenly release the second arm for free movementtoward the first arm, and a gradual rise from the latter to the formerportion; and a yieldable means connecting said arms and tending to holdeach in engagement with its cam.

9. Interrupter mechanism, comprising, a fixed breaker point, a pivotedarm carrying a cooperating breaker point, an actuating cam for said arm,said cam having a dwell portion for holding thearm so positioned thatthe points are separated, a let off portion for suddenly releasing thearm for free movement, and a gradual rise from the latter to'the formerportion; a second pivoted arm having a part adapted when the arm isreleased to engage and suddenly move the first arm, an actuating cam forthe second arm, and said cam having a dwell portion to hold the secondaway from the first arm,

a let off portion to suddenly release the second arm for free movementtoward the first arm, and a gradual rise from the latter to the formerportion; and a yieldable means connecting said arms and tending to holdeach in engagement with its cam, the second cam arranged to release itsarm shortly after the release of the first arm by its cam and before thefirst arm is moved by the rise portionpf its cam.

10. Interrupter mechanism, comprising a fixed breaker point, a pivotedarm carrying a cooperating breakerpoi'nt, an actuating cam for said armsaid cam having a dwell portion for holding the arm so positioned thatthe points are separated, a let off portion for suddenly releasing thearm for free movement, and a gradual rise from the latter to the formerportion; a second pivoted arm having a part adapted when the arm isreleased to engage and suddenly move the first arm, an actuating cam forthe second arm, said cam having a dwell portion to hold the second awayfrom the first arm, a let off portion to suddenly release the second armfor free movement toward the first arm, and a gradual rise from thelatter to the former portion; ,and a yieldable means connecting saidarms and tending to hold each in engagement with its cam, the second camarranged to release its arm shortly after the release of the first armby its cam and before the first arm is moved by the rise portion of itscam, said yieldable means producing no turning movement of the membersaround their axis in either direction after the breaker points separate,and said rise portions arranged to move the arms to place the yieldablemeans under increased stress without closing said breaker points. 7

l1. Interrupter mechanism, comprising, cooperating and relativelymovable breaker points, rotary timing mechanism for controlling theopening and closing of said points, means operable from said mechanismat predetermined times to move said points into engagement at a speedindependent of its rotative speed, means subsequently operable from saidmechanism to move said points into separated relation and at a speedindependent of its rotative speed, and damping means associated with oneof said points to prevent rebounding of the movable point and prematureseparation of the points following the engagement of the latter.

l2. Interrupter mechanism, comprising, cooperating breaker points, a camhaving a dwell portion for holding the points in separated relation anda sharp let oil portion for suddenly releasing the points to permitengagement thereof, a hammer :Eor suddenly separating the points, a camcontrolling the hammer and having a dwell portion to hold it in inactiveposition and a sharp let off portion to suddenly release it for action,and

resilient means for actuating the hammer and said points when released.

13. Interrupter mechanism, comprising, cooperating breaker points, a camhaving a dwell portion for holding the points in separated relation, anda sharp let off portion for suddenly releasing the points to permitengagement thereof, a hammer for suddenly separating the points, a camcontrolling the hammer and having a dwell portion to hold it in inactiveposition and a sharp let off portion to suddenly release it for action,and resilient means for actuating the hammer and said points whenreleased; the second cam releasing the hammer at a definitepredetermined time after the release of said points.

In testimony whereof I have afiiXed my signature.

HAROLD H. CLARK.

